Thermally conductive interface materials are widely utilized in the electronics industry for operably coupling heat-generating electronic components to heat-sinking structures. Most typically, such thermally conductive interface materials are utilized in connection with heat-generating electronic components such as integrated circuits (IC), central processing units (CPU), and other electronic components containing relatively high-densities of conductive traces and resistor elements. In particular, the thermal interface materials are often times utilized to operably couple such heat-generating electronic devices to heat sinking structures, such as finned heat sink structures. In such a manner, excess thermal energy generated by the electronic components may be expelled to the heat sinking structures via the thermal interface material.
Certain electronic devices, in addition to generating excess thermal energy, create electromagnetic radiation across various frequencies. Such radiation can have the effect of causing electromagnetic interference (EMI) and/or radio frequency interference (RFI) with other electronic devices susceptible to and/or tuned to receive electromagnetic or radio frequency wave forms. Devices sensitive to electromagnetic and radio frequency interference include, for example, cellular phones, portable radios, laptop computers, and the like.
As the prevalence of portable electronic devices which are sensitive to electromagnetic and/or radio frequency interference increases, manufacturers of internal electronic componentry for such devices have incorporated electromagnetic radiation-absorbing substances into thermally conductive interface materials disposed adjacent to the electromagnetic radiation-producing devices. Constructions have therefore been implemented in thermal interface materials which bear an operating characteristic of absorbing, reflecting, or otherwise suppressing the transmittance of electromagnetic and/or radio frequency radiation through the interface. As a result, such thermal interface material constructions act to provide a thermal release pathway while simultaneously suppressing transmittance of electromagnetic and/or radio frequency radiation from the corresponding electronic component to which the thermal interface material is addressed.
The thermal interface material constructions proposed to date for providing such characteristics, however, utilize homogeneous or quasi-homogeneous dispersions of radiation suppression substances within the thermal interface material backbone matrix. In doing so, the resultant compositions render the overall construction of low electrical resistance. The relatively low electrical resistivity of conventional electromagnetic and/or radio frequency interference suppression constructions fail to adequately electrically isolate structures such as heat sinks that are operably coupled to the respective heat and interference radiation-generating electronic components via the interface. Many applications exist, however, where such electrical isolation is preferred or required.
Conventional EMI suppression materials also tend to be relatively rigid, thereby diminishing their effectiveness as thermal conductors. The lack of compliance in conventional EMI suppression interfaces results in air gaps between the EMI suppression interface and the connected components. Such air gaps act as a relative thermal barrier, and diminish the overall thermal conductivity of the interface. Moreover, the relatively non-compliant conventional interface structures can cause damage to fragile electrical components in the assembly of the heat sinking apparatus, particularly as the heat sinks or external EMI shields are press-fit onto the EMI suppression interface.
It is therefore an object of the present invention to provide an electrically isolative thermal interface material that acts to operably suppress transmittance of electromagnetic and/or radio frequency radiation.
It is a further object of the present invention to provide an electrically isolative thermal interface material construction incorporating an electromagnetic and radio frequency interference suppression composition that is confined solely within a predefined portion of the thermal interface construction.
It is a still further object of the present invention to provide a thermally conductive interface product that is formed of a plurality distinct material layers, and only predefined ones of such layers contain electromagnetic and radio frequency radiation suppression material.
It is another object of the present invention to provide an electrically isolative thermally conductive interface product having the first and second major exposed surfaces being fabricated from an electrically insulative and thermally conductive material, and an electromagnetic and radio frequency interference suppression material contained solely within a portion of the interface product that is interposed between the electrically insulative portions thereof.
It is a further object of the present invention to provide a method of constructing a thermally conductive interface material having an electromagnetic and radio frequency radiation suppression characteristic, the method involving separately laying up distinct material layers having disparate compositions.
It is yet another object of the present invention to provide an electrically isolative thermal interface that is effective in suppressing electromagnetic and/or radio frequency radiation, and exhibits a low modulus so as to be compliant for improved thermal conductivity and soft for protection of electrical components in the assembly process.